The present invention relates generally to packages for use in microwave ovens, and pertains more particularly to an expandable bag having protection from grease leaking and/or wicking from its expansion creases or folds and/or to a flexible popcorn package made from a single layer of greaseproof paper.
When microwave popcorn packages were first introduced utilizing a microwave susceptor, the packages typically were formed by expandable paperboard containers and often the load of the microwave popcorn popping package was located in a plastic bag positioned inside of the paperboard container including the microwave susceptor. The paperboard container in most instances was unfolded into an expanded size by the consumer prior to popping of the popcorn kernels in the microwave oven but in some instances was unfolded by the popping of the popcorn kernels, with the popped popcorn being served in the expanded paperboard containers. Early packages suffered from several disadvantages including the bulk of expandable paperboard containers which increased the amount of material required to make the container and thus its cost, increased the size of the packaging and storage requirements, as well as increased the amount of material which had to be disposed of after the consumption of the popcorn raising environmental concerns. Further, the dynamics of expanding the paperboard container and/or plastic bag by the forces generated while popping the kernels were typically insufficient to maximize the volume of the package which in turn prevented the popcorn from popping with greater volume. Also, plastic bags are susceptible to melting and often are difficult to handle with a hot food product at least due to the poor insulating qualities of plastic. To avoid these and other problems and with the development of microwave susceptors applied in the form of a thin coating such as disclosed in U.S. Pat. No. 4,267,420 issued to William A. Brastad, the microwave popcorn industry has turned to popcorn packages formed from flexible paper bags.
However, paper microwave popcorn popping bags including microwave susceptors encountered different types of problems. For example, the load of a microwave popcorn popping package includes unpopped popcorn kernels, a cooking oil or grease, salt, and other ingredients such as colorings, flavorings, or the like. It can be appreciated that during storage or transportation of the filled microwave popcorn package by the processor, the marketing agencies, and the consumer, the oil and/or grease have a tendency to leak from flexible paper packages, especially at high temperatures, causing aesthetically unpleasant appearances. Further, during microwave popping, the oil and/or grease have a tendency to wick from flexible paper packages. Current flexible paper popcorn bags such as disclosed in U.S. Pat. No. 5,044,777 typically use a tri-laminate of a greaseproof paper adhered to an outer fluorocarbon treated, grease resistant paper with a microwave susceptor sandwiched between. For example, the inner layer could be formed of bleached greaseproof Kraft paper of 11.5 kg. (25 lb.)/ream basis weight and the outer layer could be formed of plain bleached Kraft paper of 13.5 kg. (30 lb.)/ream basis weight. The two paper layers and the adhesive therebetween together provide the needed grease barrier in both storage and/or transportation at high temperatures as well as during microwave cooking. However, laminated paper popcorn bags suffer from several disadvantages. First, the paper bag has a great deal of stiffness resulting from the multiple layers themselves but also their adhesive interconnection. Stiffness detracts from the ability of the bag to inflate or expand during microwave popping of the popcorn which may in turn detrimentally affect the volume of the popped kernels. Also, the lamination of the materials requires extra assembly costs and the amount of materials used for each bag adds to the economic and environmental costs.
Thus, there is a need to reduce the amount of material and/or layers utilized in the formation of flexible paper popcorn packages including a microwave susceptor. Current efforts in single ply paper bags which have been unsuccessful prior to the present invention involve common greaseproof paper in combination with surface coatings of fluorocarbons, such as FC-807 made by 3M, Inc., St. Paul, Minn., or equivalent. However, such efforts have not resulted in commercially successful packages as they do not provide adequate greaseproof properties in storage, transportation, or cooking throughout the paper. Further, when this paper is creased such as at the corners in the pleats and between the pleats and the top and bottom walls, fibers in the paper and the coatings applied thereto fracture and separate and reveal Uncoated fiber ends which absorb grease. Moreover, breaks or fractures might occur and the oil and/or grease can leak out of the package.
Consequently, there is a continuing need for a flexible paper popcorn package with reduced layers and particularly formed of a single layer of flexible paper.
Further, as set forth above, the problem of grease wicking and actual leaking is especially present at folds and creases where the fibers of the paper and coatings applied thereto for the greaseproofing characteristics are fractured and/or separated. This problem has been one of the major factors in limiting the amount that the material and/or number of layers can be reduced in flexible paper popcorn bags, as the mass and number of layers of material are relied upon to provide the needed grease barrier. Thus, a need exists for optionally providing an added grease barrier at only those locations especially at folds and creases where grease wicking and leaking are a problem, with the added grease barrier allowing minimization of the material and/or number of layers at the remaining locations where grease wicking and leaking are not such a problem.
Surprisingly, the above needs and other objectives can be satisfied by providing a package in the form of a bag including grease protectors for sealing the surfaces of the walls of the bag adjacent to their connecting, folding edges to prevent the grease or oil from leaking or wicking from the interior volume of the bag.
In a preferred aspect, the package includes pleated, expandable side walls, with the grease protectors located inside of the bag where the inside surfaces of the pleats overlie other inside surfaces of the bag and also located outside of the bag where the outside surfaces of the pleats overlie other outside surfaces of the bag.
In yet another preferred aspect of the present invention, the bag holds popcorn kernels and grease or oil for popping in a microwave oven, with the bag formed of a single layer of greaseproof paper having a thickness allowing the single layer to be flexed by the popping of the popcorn kernels and also preventing the wicking and leaking of the grease or oil through the single layer.
The present invention will become clearer in light of the following detailed description of an illustrative embodiment of this invention described in connection with the drawings.